Auto merge of #2908 - froydnj:spelling-fixes, r=alexcrichton
Auto merge of #2908 - froydnj:spelling-fixes, r=alexcrichton

fix typos in src/doc/manifest.md

A few things I noticed while reading the documentation.  The "sections" change is not strictly a spelling error, but I figured I would fix it while I was in the area.

rust-lang/cargo,AndiDog/cargo,vojtechkral/cargo,sbeckeriv/cargo,AndiDog/cargo,sbeckeriv/cargo,eminence/cargo,brson/cargo,AndiDog/cargo,brson/cargo,nipunn1313/cargo,tsurai/cargo,tshepang/cargo,AndiDog/cargo,vojtechkral/cargo,tsurai/cargo,brson/cargo,eminence/cargo,rustyhorde/cargo,tshepang/cargo,achanda/cargo,brson/cargo,rust-lang/cargo,rust-lang/cargo,nipunn1313/cargo,rustyhorde/cargo,eminence/cargo,vojtechkral/cargo,brson/cargo,achanda/cargo,tsurai/cargo,nipunn1313/cargo,vojtechkral/cargo,nipunn1313/cargo,durka/cargo,achanda/cargo,rustyhorde/cargo,AndiDog/cargo,sbeckeriv/cargo,tshepang/cargo,rust-lang/cargo,achanda/cargo,eminence/cargo,rustyhorde/cargo,durka/cargo,tsurai/cargo,durka/cargo,tshepang/cargo,sbeckeriv/cargo,durka/cargo,tsurai/cargo